Engine Intro & Basic Induction

1. Engine Intro & Basic Induction Presented by: Will Miller

2. Engine Types • Turbine Engine • Found in transport Category aircraft • Relatively costly but extremely powerful • Reciprocating Engine • Found in general aviation • Economical, but still very reliable

3. Cessna Engine • Horizontally Opposed • Direct Drive • Air Cooled • 4 cylinder

4. Engine Operation • What are the four strokes of an engine?

5. Four Strokes on an Engine

6. Intake • When the piston moves away form the cylinder head • Intake valve opens • Fuel/Air mixture is drawn into the combustion chamber

7. Compression • Piston moves back toward the cylinder head • Intake valve closes • Fuel/Air Mixture is compressed

8. Power • Compression nearly complete • Spark plugs fire • Compressed mixture is ignited • Rapidly expanding gases drive the piston, providing the power that rotates the crankshaft

9. Exhaust • Expels the burned gases through the exhaust valve, which opens at the end of the power stroke

10. Induction System • Brings outside air into the engine, mixes it with fuel in the proper proportion and deliver it to the cylinders where combustion occurs. • Throttle • Mixture • Intake Port

11. Throttle • Controls Engine Speed • Regulates the amount of fuel/air mixture that flows into the cylinders

12. Mixture • Controls the fuel/air ratio

13. Intake Port • Where outside air enters the induction system • Normally contains an air filter to keep out dust and FOD

14. Carburetor • Mixes the incoming air with fuel and delivers it to the combustion chamber

15. Carburetor • Air passes through a venturi, increases velocity and decreases pressure • Fuel enters from a float chamber where it is maintained at a nearly constant level by a float device • Discharge nozzle is located in an area of low pressure created by the venturi • Fuel is forced through the discharge nozzel by the higher atmospheric pressure in the float chamber

16. Overly Rich Mixture • What does it mean to have a “Rich” mixture? • As altitude increases, the mixture will get progressively richer due to the decrease in air density. • Can result in engine roughness: excessive carbon buildup on the spark plug will cause them to foul. • High elevation airports, climb or cruise at high elevation

17. Overly Lean Mixture • What does it mean to have a “Lean” mixture? • May result in high engine temperatures causing excessive wear or even failure • Enrichen Mixture on descents from high altitudes • Watch engine temperature

18. Carburetor Ice • Occurs due to the effect of fuel vaporization and decreasing pressure in the venturi which causes a sharp temperature drop in the carburetor • If water vapor in the air condenses when the carburetor temperature is at or below freezing, ice may form on internal surfaces of the carburetor, including the throttle valve • Likely below 21C (70F), humidity above 80%

19. Carburetor Ice

20. Carburetor Ice

21. Carburetor Ice Indications • Why can Carburetor Ice be dangerous? • What are some indications of Carb Ice? • Drop in engine RPM • Engine Roughness • Fuel starvation • What can we do to get rid of carburetor ice or even prevent it from happening in the first place? • Carburetor Heat

22. Carburetor Heat • Carburetor ice is especially dangerous when operating at low power settings, may go unnoticed until power is added • How does carburetor heat work? • Carburetor heat routes air across a heat source before it enters the carburetor • How will carb heat affect engine performance? • Causes a slight decrease in engine power (heated air is less dense) • If ice is present, there will be a decrease followed by a gradual increase in rpm

23. Carburetor Heat